Consolidated Statements Of Income (Loss) And Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018
OPERATING REVENUES
Earned premiums		$ 1,203,977		$ 1,151,021
Net investment income		114,182		108,016
Net realized investment gains (losses)		681		(946)
Change in fair value of equity securities		611,510		(122,052)
Net investment gains (losses)		612,191		(122,998)
Products Revenues		348,794		294,136
Services and other revenues		193,344		145,296
Total Operating Revenues		2,472,488		1,575,471
OPERATING EXPENSES
Losses and loss adjustment expenses		687,746		615,118
Underwriting, acquisition and insurance expenses		455,212		424,390
Products expenses		319,426		269,697
Services and other expenses		174,606		132,433
Amortization of intangible assets		40,668	[1]	28,823	[2]
Total Operating Expenses		1,677,658		1,470,461
Operating Income		794,830		105,010
Interest expense		40,290		40,059
Net foreign exchange losses		21,864		22,114
Income (Loss) Before Income Taxes		732,676		42,837
Income tax expense		155,163		108,431
Net Income (Loss)		577,513		(65,594)
Net income (loss) attributable to noncontrolling interests		1,086		(1,288)
Net Income (Loss) to Shareholders		576,427		(64,306)
OTHER COMPREHENSIVE INCOME (LOSS)
Net holding gains (losses) arising during the period		152,331		(116,922)
Reclassification adjustments for net gains (losses) included in net income (loss)		(246)		814
Change in net unrealized gains on available-for-sale investments, net of taxes		152,085		(116,108)
Change in foreign currency translation adjustments, net of taxes		2,377		4,953
Change in net actuarial pension loss, net of taxes		1,361		664
Total Other Comprehensive Income (Loss)		155,823		(110,491)
Comprehensive Income (Loss)		733,336		(176,085)
Comprehensive income (loss) attributable to noncontrolling interests		1,091		(1,246)
Comprehensive Income (Loss) to Shareholders		$ 732,245		$ (174,839)
NET INCOME (LOSS) PER SHARE
Basic (in dollars per share)		$ 42.81		$ (4.25)
Diluted (in dollars per share)	[3]	$ 42.76		$ (4.25)

[1] Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.

[2] Segment profit for the Markel Ventures segment includes amortization of intangible assets attributable to Markel Ventures. Amortization of intangible assets is not allocated to any other reportable segments.

[3] The impact of restricted stock units and restricted stock of 27 thousand shares was excluded from the computation of diluted earnings per share for the three months ended March 31, 2018 because the effect would have been anti-dilutive.